Switching converters are widely used in the field of power conversion. A switching converter includes at least one switch that is configured to generate a pulse-width modulated (PWM) voltage from an input voltage, and a rectifier arrangement that receives the PWM voltage and generates an output voltage to be supplied to a load. Usually the rectifier arrangement includes at least one inductive storage element, such as a choke, and at least one capacitive storage element, such as a capacitor. The PWM voltage is generated by switching the switching element on and off in accordance with a PWM drive signal. The PWM drive signal is provided by a controller dependent on the output voltage. The controller is configured to vary, e.g., the switching frequency of the PWM drive signal in order to maintain a desired output voltage.
LLC converters, sometimes referred to as resonant LLC converters or LLC power converters, have been widely used recently due to desirable features such as high efficiency, low electro-magnetic interference (EMI), and high power density. A characteristic feature of an LLC converter is a resonant circuit on the primary side of the converter that includes a resonant capacitor, a resonant inductor, and the magnetizing inductance of the transformer. During operation, the amount of energy transferred by the LLC converter may be controlled by controlling the switching frequency at or about the resonant frequency of the resonant circuit.